1. Field of the Invention:
The present invention relates to a method for recording signals on, and reproducing them from, a film suitable for use in recording aural signals on, and reproducing them from, a sound track of a motion-picture film.
2. Description of the Prior Art:
FIGS. 1, 2 and 3 are schematic representations showing a method for recording signals on, and reproducing them from, a conventional film previously introduced in for example "Film Technology, Broadcasting Technical Library" (published by Japan Broadcast Publishing Co., Ltd ). In FIG. 1, numeral 1 is a film, for example a motion-picture film; numeral 2 denotes perforations for carrying the film 1; numeral 3 is an image frame; numeral 4 indicates an optical sound track section provided along the longitudinal direction of the film 1; numeral 16 denotes an arrow indicating the direction of travel of the film 1; numeral 17 denotes a recording light beam with intensity converted from a sound signal, or a recording light signal for recording variations in the surface area of a photosensitive part of the sound track section; numeral 18 denotes a reproducing light beam to be used for the reproduction of sound in the sound track section 4; numeral 14 represents a light detector which converts the reproducing light beam 18 that has passed through the film 1 into an electric signal; numeral 19 is an enlarged view of the sound track section 4 where recording is performed by a variable density recording method; numeral 20 is an enlarged view of the sound track section 4 where recording is performed by a variable area recording system.
In FIG. 2, numeral 4 denotes a magnetic sound track section coated with a magnetic substance; and numeral 21 expresses a magnetic head which records signals on the sound track section and reproduces signals therefrom.
In FIG. 3, numeral 22 is a tape of the same shape as the film; numeral 4 is a wide magnetic sound track section provided between the perforations 2 on both sides of the tape 22; and numeral 21 is a magnetic head which records signals on the sound track section 4 and reproduces signals therefrom.
Next, the operation of the prior art will be explained.
In FIG. 1, in the recording mode, the recording light signal 17 obtained by converting an aural signal is recorded on the sound track section 4 through light exposure. The recording system that converts the aural signal into light intensity is called the variable density system in which, as shown in the enlarged view 19, the strength of a recording light signal is recorded as a variation in the density of the film 1. The recording system in which the aural signal waveform is converted into a variation in the photosensitive surface area of the sound track section 4 is called a variable area system, which records as shown in an enlarged view 20. In the reproduction mode, the reproduction light 18 is projected into the sound track section 4, and the light that has passed through is converted into an electrical signal by the light detector 14.
Next, in FIG. 2, in the recording mode, the aural signal is supplied to the magnetic head 21, for electrically recording the signal on the sound track section 4. In the reproduction mode, the aural signal is magnetically reproduced from the sound track section 4 by means of the magnetic head 21.
In the case of FIG. 3, a tape recorder using a tape 22 of the same shape and size as the film is used as external equipment and aural signals are recorded on, and reproduced from, the wide sound track section 4 by the magnetic head while the tape recorder and the projector are simultaneously driven on the basis of external synchronizing signals that can be obtained by using a tape recorder loaded with a tape 22 of the same shape and size of a film as an external equipment and by counting perforations of a projector film.
According to the conventional method, recording signals on, and reproducing them from, a film are carried out as described above. However, there is a problem, in the case of FIG. 1, that the sound characteristics vary with the type and the method of development of the film 1; the reproduction signal waveform is distorted by halation and flare on the film; and furthermore when a copy is to be reproduced from a master film, the sound characteristics are deteriorated by the aberration of the optical system at the time of copy reproduction. Also in the case of FIG. 2, the magnetic substance coated on the magnetic sound track section 4 is inferior in flatness and in addition since a hard and thick film base is used, the magnetic substance surface is likely to float off from the magnetic head 21, thereby giving an adverse effect to sound quality. Also when reproducing a copy, it is necessary to produce both an optical copy of the image 3 and a magnetic copy of the sound track section 4. Furthermore, in the case of FIG. 3, since the tape 22 is of the same size as the film, the tape recorder to be used must be a large size and costly.